Fantastic theories about the future of microscopic science abound, but biomedical researchers exploring the molecular world of nanotechnology are developing new devices, more effective drugs, new delivery systems and a host of tiny diagnostic devices that offer significant advances in treating patients in the near future. "I'm a big believer that this technology will have a huge impact," says Dr. Aaron Fleischman, a biomedical engineer at the Cleveland Clinic who has been researching miniaturized versions of drug delivery systems and new methods for ultrasound images. "Five years from now," adds Dr. Fleischman, "I see better targeted drug delivery and a whole host of tissue engineering capabilities. I think the area of coatings and the area of materials is really the most promising." Because nanotechnology works on a molecular level, its products can become more easily integrated with the body. By changing the molecular structure of the surface of an implantable knee, for example, researchers can make them bond better with the surrounding tissue. For Dr. Fleischman, the work involves both nanotech scale, which is measured on a scale in which 70,000 nanometers stretch across the expanse of single human hair, and microelectronics, which operates on a scale of a cubic millimeter. BioMEMs has helped pioneer a host of new devices, including a new generation of pacemakers. Now, says Dr. Fleischman, researchers like him are aiming at a confluence of the two fields, developing new tissue engineering and bone regeneration. And he's hardly alone. The biomedical side of nanotechnology has been expanding swiftly in recent years. Biophan Technologies, for example, has been developing nanomagnetic particles that can bind to human tissue, making pieces of the anatomy appear in sharp relief when physicians are viewing various parts in the body with magnetic resonance imaging devices. And one of its subsidiaries recently signed a deal with NASA's Ames Research Center for Nanotechnology to study ways of using nanoengineered thermoelectric materials with implantable medical devices. At Emory University, scientists have used quantum dot - luminescent crystals the size of a nanometer - technology to target and image cancerous tumors. Because of their structure, the crystals emit different colors of light that work as a tag. Wrapped in a polymer coating, researchers attached the quantum dots to antibodies that in turn guided them to prostate tumors in mice. The quantum dots were visible under a mercury lamp. The advantage is that the dots can be attached not only to antibodies, but peptides and proteins and used to probe for specific molecules. And researchers say that it may well prove a major advance in targeting, identifying and treating cancer in humans. "We believe biomedical nanotechnology will soon produce major advances in molecular diagnostics, therapeutics, molecular biology and bioengineering," said Dr. Shuming Nie, PhD, professor in the Coulter Department of Biomedical Engineering at Emory University and the Georgia Institute of Technology and director of cancer nanotechnology at Emory's Winship Cancer Institute at a meeting of the American Chemical Society. Dr. Nie and others in the field have been developing nanoprobes that can analyze tissue, measure the effectiveness of drugs and control the delivery of drugs into cancer cells. And researchers working with The Children's Hospital in Philadelphia have been developing cardiovascular tissues that can improve blood supply and patch damaged sections of heart muscles. But while much of the early work in medical nanotechnology is likely to be concentrated in sophisticated research centers, Dr. Fleischman also says the technology is being developed so it can go directly into the hands of frontline practitioners. "It will be transparent to the end user. It won't take another degree to use these devices. All the researchers are focused on making these fit in with existing medical paradigms." But it isn't simple work. "I think the biggest challenge from a technological point of view is that the area is so broad," says Dr. Fleischman. The work requires multidisciplinary teams of skilled experts in a variety of fields, covering everything from the physical chemistry to nanoscale mechanics and precision fluid control. But every year the teams make a fresh set of nanotech discoveries the pushes the frontiers of medical science to an ever-smaller arena filled with bigger promises of new therapies.